High-power harvesting of mechanical energy from human locomotion is a well-known concept, but has not been widely commercialized to date due to the lack of viable energy harvesting technologies. One of the potentially important applications of high-power harvesting of mechanical energy from human locomotion is the heating of footwear—particularly outdoor footwear used in cold climates.
There are a number of popular products that are currently available to provide heat for outdoor footwear, including electrical heaters powered by batteries and specially-designed footwear inserts that chemically generate heat (i.e., an exothermic reaction upon activation of the insert). However, both of these types of devices have several drawbacks. These include the need to replace or recharge batteries for the electrical heaters, as well as the disposal and replacement of the exothermic elements once the chemical reaction has been exhausted.